2003 Ford 6.0 Hard start below 60f.

gmw photos wrote:
Do a load test on both batteries. We had one of the two that had shorted cells, and it was dragging the other down with it. It "seemed" to spin pretty fast, at least just from listening to it. But once I put two new interstate batteries in it, it spun faster, and the tech told me that also this would allow for higher FICM voltage while cranking. Fixed our hard start issues.

X2,
Had a friend with a F350 6.0, and a no start condition. I attempted to jump start him with no luck, replaced both batteries, and the alternator, and all better.
The FICM checked out fine while I was jumping him.

This is why I love my VP44 Cummins only need about half a revolution to start!

Do a load test on both batteries. We had one of the two that had shorted cells, and it was dragging the other down with it. It "seemed" to spin pretty fast, at least just from listening to it. But once I put two new interstate batteries in it, it spun faster, and the tech told me that also this would allow for higher FICM voltage while cranking. Fixed our hard start issues.

My FMP IS 47.5 to 48.0 before and while cranking.I do not hear the glow plug sound before starting.

You need a minimum of 500# ICP, and IIRC 150rpm cranking, before the PCM will fire the injectors. Slow starts are usually one of those two issues. On an '03 it could simply be the ICP sensor, which is in a bad location. Or could be injection pressure is leaking from the usual suspects. Load test your batteries to be sure they are cranking strong. Often can't tell by just listening.

FICM volts maybe, but 47.5 is good. Trick is to watch the FICM volts before, during, and after cranking. Voltage should hold in all those different modes.

And of course glow plugs, but the glow plug monitoring is very good on the 6.0. The GPCM is still a possibility. The monitoring is good, but not perfect.

Had the same problem. Hard to start and ran like******until up to temp then ran fine after that.
Never had any codes and fuel mileage was not off just ran bad for 5 minutes.
New injectors and dummy plugs in fuel rail made it run like new. Mileage at the time was 130,000

Son has a 06 6.0 that had the same symptoms that wound up being the ficm. You need a solid 48 volts with the key on if i remember correctly , and it can't drop much when cranking.

Most likely it's your FICM (Fuel Injection Control Module). Get with Ed at FICMRepair and he'll hook you up.

I would search or post this information at Powerstroke.org . Those guys are more into trucks and less into rv's. You'll most likely get some good info there.